How to Overwinter Geraniums

Time to stop buying new geraniums each year (sorry nurseries). It is extremely simple and efficient to overwinter you geraniums so they can bloom for years to come. Geraniums have succulent stems, which makes them fairly drought tolerant and easy to store overwinter.

I used to spend hundreds of dollars each year buying new geraniums (I know what you are thinking, but there is no such thing as too many flower pots), and at some point each winter a snow or cold spell would sweep through in January or February and kill any left outside (zone 8B in the Seattle area). Surprisingly, geraniums are pretty hardy and can easily handle a frost, but I've found that when it snows more than a couple of inches that is what does them in.

A few years back, I was suffering from the PacNW fall blues while planning my next year's garden and came across some articles about overwintering geraniums... total mind blown. At this point it was November and my geraniums were still green with a couple of scattered blooms, so I figured why not give it a try? Worst comes to worst I just buy new geraniums in the spring. I was shocked by how easy and successful overwintering geraniums was, and I think you will be too. I think I usually have about a 90% success rate storing them in paper bags and close to 100% when moving the containers indoors.

Ways to Overwinter Geraniums

Storing in Paper Bags:

1. Dig up your geraniums and wash away the dirt around the root ball. In the Maritime PacNW I usually do this in late Oct or early Nov. Geraniums are fairly hardy, but you do need to remove them before it snows or there is a very hard frost.

2. Let the stems and roots dry out in a dry, covered location for 12-24 hours. If it is a sunny day you can let them dry out in the sun for a few hours. We just want to get the extra water off the plants to reduce any chance of mold

3. Once dry, cut off all of the the leaves, small stems, and flowers. For larger stems you can cut back each stem by roughly 20-40% depending on their length. Cut right above a leaf node which is where the new growth will come out of. If you plan to propagate them in the winter/spring, you can also consider not or minimally trimming back the larger stems.

You can see leaf nodes along this stem for reference:

4. Transfer to a paper bag (you can place quite a few in one bag) then loosely roll the top of the bag and store in a cool, dark, dry location (garages work great for this). I store ours in our unheated, unfinished basement. You do not want it to be warm or bright, else they will just start growing.

5. Every 4-5 weeks check on the geraniums and let their roots soak for an hour, then transfer back to the bags. If there are any dead spots or new growth on the stems then cut them back - I generally just do this 1-2 times during storage. You can identify a dead spot by the coloring (it will be brown/black) and it will generally be soft and/or hollow. A healthy stem after soaking the roots should be nice and firm, if there are any dead spots just trim the stem back until you feel firmness and/or it becomes green.

6. Remove from the paper bags and plant in a small nursery container filled with potting soil. If you have a greenhouse or cold frame you can usually do this starting in early to mid-March. If you have indoor grow lights or a sunny spot indoors you can start them in early to mid- Feb. Let grow in the nursery pots until early-mid April then transplant into the garden or pots.

Overwintered stems 1-2 weeks after planting in nursery pots and starting in cold frame in March:

Overwintered stems 2-3 weeks after planting in nursery pots and starting under grow lights in late January:

The geraniums above transferred out to the cold frame in early March. On the far right you will see a stem that should have been trimmed back further or used to propagate which will encourage more fullness vs leginess:

A note about propagation - I generally propagate geraniums during Step 6, but I bring those propagated stems indoors for about a month. I think the success rate is usually around 75%, so this is a great way to replace any plants that did not make it through the winter storage or to expand your selection. To propagate I just cut a large stem at an angle then place directly in moist potting soil - usually roots grow within a few weeks. If you'd like to ensure they reach their full potential in size for that season, you can consider doing this in early-mid February and keeping indoors until April.

Storing in containers:

If you have your geraniums planted in containers that can be brought into the garage or a crawl space, all you need to do is remove the small stems, leaves, and flowers then transfer the entire container into its cool, dark, dry spot for winter storage. Check on it each month, and if it feels dried out apply a little water. Generally the ones I store in containers I water 1-2 times over the 5 month period. I generally trim the stems by 30-40% before moving back outside for Spring (you can also do this before transferring them into winter storage) - this will reduce any leginess and ensure a full geranium with loads of flowers.